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  • Writer's pictureTrevor Rook

How much can solar panels reduce my electricity bill?




There are lots of factors used to calculate the savings achieved by installing solar panels. As qualified solar installers, part of the training we receive is how to calculate these savings. Using an MCS certified RECC member ensures that we have had our processes inspected to ensure the way we calculate and communicate savings to potential customers is fair and reasonable. It’s a common theme through our blogs but its really important to ensure you check your potential installer is both RECC and MCS certified. Unfortunately, some of the rogue traders, who mainly left the industry when the FiTs scheme was withdrawn, are now starting to reappear.

MCS logo amd RECC logo

In terms of savings, I can’t tell you exactly what the saving will be for your individual circumstances. Each quote we provide is tailored (which is when you make an enquiry, you’ll find that initially we ask for lots of information from you). Each roof is different with size, orientation and pitch effecting how many panels we can install and how much power they produce. Shade from trees or chimneys will also have an impact. All these factors are considered whenever we state how much energy you’ll produce. We also ask about how much energy you will consume, your household type and if you’re in or out during daytimes. All these factors effect how much of the produced energy is used within your home, and how much is exported to the grid. If we are combining a battery with your solar panels we’ll calculate the savings in line with the tabulated values provided by MCS. Sometimes if you have a particularly large use, or large PV installation you’ll be outside the range of these tables and we’ll use the same method to produce the tables to provide an estimate.


Performance for an ‘average roof’

In an ideal world (for solar), all roofs would be south facing. That isn’t the case, so lets assume our example roof faces south-east, -45 degrees from south. The optimum roof pitch for this orientation would be 39 degrees, but lets assume 43 degrees for this example. We’ll also assume we have some minor shading from trees around 10M away which impact performance slightly. We’ll use the UK mean average electricity usage of 3500kWh per year and assume the house is occupied half of the day.

For the system, we’ll assume we can install 10x 415W panels. We’ve selected a GivEnergy 3.6kW hybrid inverter and 5.2kWh battery as most suitable for this install.

Knowing all the above, we can now produce a performance estimate with self consumption (both with and without solar).


Section C shows grid independence PV only at 26%. This would represent a 26% saving on the amount of electricity purchased. The remaining 2581kWh produced would be exported to the grid and a payment can be received via SEG (smart export guarantee).

Section D shows the grid independence PV with EESS (Electrical Energy Storage System, the 5.2kWh battery). This would represent a 66% saving on electricity purchased. The remaining 1203kWh produced would be exported to the grid and a payment can be received via SEG (smart export guarantee).

The electricity market cap varies across the country, but in our area its 34.6p per kWh currently. PV only would save £ 317.97 annually in this example. The current best export only tariff is British Gas at 6.4p per kWh and would generate £186.24 annually. The total saving would be £ 504.21

PV with battery would save £ 794.76 on purchased electricity with an addition SEG payment of £ 98.04. Total savings £ 892.80 annually, or £ 74.40 per month.

Octopus currently offer the best SEG rate at 15p per kWh, if you’re with them for supply, which could enhance the SEG element.


How much can solar panels reduce my electricity bill?

Significant savings are possible, calculated with MCS approved methods. And a reminder, this isn’t a perfect roof, usage amount or usage type. You may be able to save more, get in touch for a tailored performance estimate.

There are additional sources of revenue and savings open to battery owners. Either using cheap off peak power or being incentivised to export/ avoid use at peak times. Fantastic potential with modern smart tariffs like Octopus Flux recently being launched in the UK.


Ready to start to investigate solar for your property or business premises? Get in touch with us for a quote CONTACT US or read more about Solar and Home Batteries CLICK HERE.

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